Portable computers enable users to perform computing tasks and to carry the computer from one location to another with few constraints. Although portable computers give users tremendous flexibility, such machines may only run a limited number of external devices without compromising portability. The need to run external devices gave rise to the expansion device, typically referred to as a docking station. A docking station allows a portable computer to be connected to numerous peripherals, such as CD-ROMs, modems, SCSI devices, monitors, local networks and ISDN lines.
For several years now, AT-compatible systems and chipset vendors have offered options to insert and remove a portable computer to and from an expansion device. These previous methods are typically grouped into "cold-docking" and "warm-docking" solutions. Cold-docking is insertion or removal of the portable computer while both the portable and expansion device are completely powered off. Warm-docking is insertion or removal during a power-managed state, including suspend-to-disk (0V) and suspend-to-RAM (5V/3V) suspend modes.
Both cold-docking and warm-docking methods of insertion and removal were designed to prevent data loss and system damage. However, one difficulty with using previous methods is that a user must manually place the docking bus into a power-off or power-managed state before insertion or removal may occur. If a user inserted or removed a fully-powered portable to or from an expansion device, complete data loss and serious damage may occur. Therefore, if a user erroneously inserted a fully-powered portable into an expansion device, the systems may hang or serious, permanent damage may occur to both devices. Thus, previous methods of inserting or removing a fully-powered portable to or from an expansion device have imposed severe performance and user limitations.